This invention broadly relates to a particle separator for a gas turbine engine providing for improved particle separation by increasing the splitter hiding height, decreasing the radius of curvature of the humped-shaped portion of the inner wall after the peak of the humped-shaped portion, and providing active boundary layer control along the inner wall after the peak and within the main air flow passageway. This invention further broadly relates to a method for providing such active boundary layer control along the inner wall after the peak and within the main air flow passageway.
Aircraft gas turbine engines may be susceptible to damage from foreign objects introduced into air inlets of the engines. This problem has been most acute in the past with respect to relatively large foreign objects such as stones, gravel, birds and hail.
With the advent of gas turbine powered helicopters and other vertical takeoff and landing (VTOL) aircraft, smaller particles of foreign matter such as sand and dust have become increasingly troublesome due primarily to the conditions under which such VTOL aircraft may be operated. The advantage of VTOL capability makes such aircraft particularly useful in areas where conventional air fields do not exist, for example, in combat zones and other isolated areas. VTOL aircraft may be also specially suited for certain low-altitude missions over both land and sea. Under these and other similar conditions, substantial quantities of small foreign objects such as sand, dust, etc., may become entrained in intake air supplied to the gas turbine engine. These foreign particles, which individually have relatively little effect on the engine, may cause very substantial damage when ingested into the engine in large quantities.
For example, recent experience has shown that engines in helicopters operating at low altitude in a desert environment may lose performance very rapidly due to erosion of the engine blading due to the ingestion of sand particles, dust particles, etc. Similar problems may occur when operating over salt water because of the heavy ingestion of salt-water droplets which may cause both corrosion and destructive erosion of turbine structures.
Gas turbine engines, including those used in VTOL aircraft often include an intake for receiving all of the air entering the engine and a compressor inlet for receiving air entering the engine compressor. Each engine may further include interior walls defining a main or primary flowpath for air traveling from the intake to the compressor inlet. In order to reduce the ingestion of foreign particles, such as sand, dust, salt, etc., by the engine, a particle separator system may be employed at the compressor inlet for scavenging foreign particles from the engine intake air. Such separator systems may include, for example an annular partition, or splitter lip, appropriately positioned in relationship to the primary flowpath so that when the gas turbine is in operation, air intended for use by the compressor is directed along one side of the splitter lip, while foreign particles carried by the air entering the intake are directed along the other side of the splitter lip (often referred to as the “scavenge” pathway or flow) for collection and subsequent removal. See, for example, commonly assigned U.S. Pat. No. 3,832,086 (Hull, Jr. et al.), issued Aug. 27, 1974; U.S. Pat. No. 4,265,646 (Weinstein et al.), issued May 5, 1981; and U.S. Pat. No. 4,527,387 (Lastrina et al.), issued Jul. 9, 1985.
Accordingly, it would be desirable to provide a particle separator system which: (1) improves particle separation efficiency; (2) without affecting or minimizing the effect on air flow to the compressor that may undesirably affect engine performance.